Arbitrary code execution in QubesOS via copy-to-VM error reporting backchannel
58 points by vntok 4 hours ago | 17 comments

sdcfgy 33 minutes ago
Reminds me of Theo DeRaadt again: https://marc.info/?l=openbsd-misc&m=119318909016582
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fallat 18 minutes ago
Brutal

I hope when people read this though they understand this is a communication style; they're clearly trying to strongly discourage people from thinking they are suddenly protected. Effective? Maybe at one time, where "macho dev energy" was a thing. Today, not so much. You can tell they mean well because the intro sentence is actually pretty cheeky!

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throwa356262 22 minutes ago
Theo is a very insightful guy, but also very opinionated. I think the truth is somewhere in between.

Especially as more and more virtualization functions move into hardware, not using them as a second security barrier seems foolish.

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XMPPwocky 19 minutes ago
Looks like this has nothing to do with the hypervisor, it's not a traditional VM escape
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12995816 21 minutes ago
Peak Theo! This refreshing truth telling has been eradicated in 2026.
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msm_ 56 minutes ago
Wow, this is serious. Makes you think, that even though QubesOS attack surface is so tiny (well-designed to be secure) there are still vulnerabilities to be found.

Worth noting that (as I understand) this vulnerability occurs only when doing copy-to-VM from Dom0:

>Note that the VM variant of `qvm-copy-to-vm` is not affected, as its version of the error reporting function does not use `system()`:

Since you should not use Dom0 for regular work, and definitely not for interacting with likely-to-be-infected VMs, the scope of this attack is smaller than it sounds. On the flip side, when it works, it elevates privileges straight to Dom0.

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zby 2 hours ago
I am still impressed by QubesOS track and I use it for my dedicated 'financials' laptop.

IMHO the thing that is holding back QubesOS is the lack of hardware acceleration for graphics - maybe now when dual monitor setups are getting popular this could be a workaround for the security considerations?

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jwrallie 2 hours ago
I dropped QubesOS once exactly for that reason in the past but now I’m running it again on a separate computer.

Even with all its drawbacks, there is something really nice about being able to run different applications over Tor, VPN or plain internet simultaneously, the ability to isolate non-safe binaries and being able to backup your VMs easily.

I wish a similar distro would be made based on KVM so that the standard kernel could be used. It would be great for compatibility.

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fsflover 2 hours ago
> I wish a similar distro would be made based on KVM

There is an Issue for that: https://github.com/QubesOS/qubes-issues/issues/7051

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artyomsv 37 minutes ago
[dead]
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polotics 2 hours ago
I'm still very impressed by qubes, and glad I'm not such a target that I feel I need the level of opsec it affords (on all my laptops).

Maybe someday AI-assisted killchains will be so widespread that Qubes is the minimal level for the (few?) still-local users of compute.

I would not have copied anything from dom0 to any another qube, the impact is low.

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TacticalCoder 54 minutes ago
I do really like the following in the bulletin:

> Important: At this point, you still don’t know whether the key you just imported is the genuine QMSK or a forgery. In order for this entire procedure to provide meaningful security benefits, you must authenticate the QMSK out-of-band. Do not skip this step! The standard method is to obtain the QMSK fingerprint from multiple independent sources in several different ways and check to see whether they match the key you just imported. For more information, see How to import and authenticate the Qubes Master Signing Key.

It looks like Qubes is ran by people who take security seriously, which is refreshing.

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leonidasrup 34 minutes ago
How well is QMSK protected from a serious attacker?
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charcircuit 3 hours ago
Another example for why system() is so dangerous to use.

I also don't understand why it needs to show the dialog in dom0. If you have the option to handle attacker controlled input on the unprivileged side, you should do that instead of putting a lot of logic on the privileged side.

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delamon 2 hours ago
The code is sloppy. They check existance of kdialog binary using full path; next step they rely on PATH search by shell. If would've been much safer to just do execve directly.
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HackerThemAll 2 hours ago
> why it needs to show the dialog in dom0

I think it's the "secure screen" that cannot be manipulated by the malware in a VM. I'd expect a password entry dialog to also be handled like that.

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charcircuit 2 hours ago
It's for an the "File copy/move error" error dialog.
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12995816 23 minutes ago
Peculiar stuff. I'm always skeptical of these security Linux distributions, but this bug is so bad that it seems like an infiltration of Qubes at best or Qubes being a honeypot at worst.
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